The huge emphasis on the environment here at the Frankfurt motor show is no surprise.

But there's more recycling going on at the Mercedes hall than might be apparent.

I was very pleased to see the original Smart concept on display alongside the latest production car. Although Smart had a rather protracted and troubled introduction (like the A-class, the chassis was heavily modified before launch to improve stability in tricky conditions) this 15 year old electric prototype shows just how far ahead of the 'green' game Mercedes managed to be.

Indeed, Frankfurt 2009 has seen serious small electric city car concepts being launched by Renault and Peugeot. The Smart was well ahead of its time - perhaps too far ahead.

The Mercedes Blue Zero electric concept is pure re-cycling. It's based on the current A-class sandwich platform, which has a space under the floor. The original A-class was supposed to be available with electric power - and the batteries were supposed to fit into the void.

However, the electric A-class was never launched. Like the Smart, the A-class was inspired by the great 'eco panic' of the early 1990s. Mercedes futurists thought that ultra short, ultra frugal city cars would become the norm by the end of the 20th century. Instead, Europe lost interest in the green agenda.

Today, though, thanks to the daily publicity surrounding the idea of man-made global warming the environment is the number one concern (apart from the economy) for the auto industry.

It seems that the work Mercedes put in nearly two decades ago on future urban transport is about to pay off.